From: Sean Christopherson <seanjc@google.com>
To: Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
Tianrui Zhao <zhaotianrui@loongson.cn>,
Bibo Mao <maobibo@loongson.cn>,
Huacai Chen <chenhuacai@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Anup Patel <anup@brainfault.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
kvm@vger.kernel.org, loongarch@lists.linux.dev,
linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 6/6] KVM: x86: Drop now-superflous setting of l1tf_flush_l1d in vcpu_run()
Date: Tue, 21 May 2024 18:40:13 -0700 [thread overview]
Message-ID: <20240522014013.1672962-7-seanjc@google.com> (raw)
In-Reply-To: <20240522014013.1672962-1-seanjc@google.com>
Now that KVM unconditionally sets l1tf_flush_l1d in kvm_arch_vcpu_load(),
drop the redundant store from vcpu_run(). The flag is cleared only when
VM-Enter is imminent, deep below vcpu_run(), i.e. barring a KVM bug, it's
impossible for l1tf_flush_l1d to be cleared between loading the vCPU and
calling vcpu_run().
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/vmx.c | 7 ++++---
arch/x86/kvm/x86.c | 1 -
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index da2f95385a12..552b6a9887a5 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6672,9 +6672,10 @@ static noinstr void vmx_l1d_flush(struct kvm_vcpu *vcpu)
bool flush_l1d;
/*
- * Clear the per-vcpu flush bit, it gets set again
- * either from vcpu_run() or from one of the unsafe
- * VMEXIT handlers.
+ * Clear the per-vcpu flush bit, it gets set again if the vCPU
+ * is reloaded, i.e. if the vCPU is scheduled out or if KVM
+ * exits to userspace, or if KVM reaches one of the unsafe
+ * VMEXIT handlers, e.g. if KVM calls into the emulator.
*/
flush_l1d = vcpu->arch.l1tf_flush_l1d;
vcpu->arch.l1tf_flush_l1d = false;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 60fea297f91f..86ae7392cc59 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11264,7 +11264,6 @@ static int vcpu_run(struct kvm_vcpu *vcpu)
int r;
vcpu->run->exit_reason = KVM_EXIT_UNKNOWN;
- vcpu->arch.l1tf_flush_l1d = true;
for (;;) {
/*
--
2.45.0.215.g3402c0e53f-goog
next prev parent reply other threads:[~2024-05-22 1:40 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-22 1:40 [PATCH v2 0/6] KVM: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load() Sean Christopherson
2024-05-22 1:40 ` [PATCH v2 1/6] KVM: Add a flag to track if a loaded vCPU is scheduled out Sean Christopherson
2024-05-22 15:16 ` Oliver Upton
2024-05-22 1:40 ` [PATCH v2 2/6] KVM: VMX: Move PLE grow/shrink helpers above vmx_vcpu_load() Sean Christopherson
2024-05-22 1:40 ` [PATCH v2 3/6] KVM: x86: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load() Sean Christopherson
2024-05-23 22:47 ` Huang, Kai
2024-05-28 19:16 ` Sean Christopherson
2024-05-29 10:50 ` Huang, Kai
2024-05-29 12:54 ` Sean Christopherson
2024-05-22 1:40 ` [PATCH v2 4/6] KVM: Delete the now unused kvm_arch_sched_in() Sean Christopherson
2024-05-24 1:50 ` maobibo
2024-05-22 1:40 ` [PATCH v2 5/6] KVM: x86: Unconditionally set l1tf_flush_l1d during vCPU load Sean Christopherson
2024-05-23 22:42 ` Huang, Kai
2024-05-22 1:40 ` Sean Christopherson [this message]
2024-05-23 22:48 ` [PATCH v2 0/6] KVM: Fold kvm_arch_sched_in() into kvm_arch_vcpu_load() Huang, Kai
2024-06-12 1:18 ` Sean Christopherson
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